Heating and ventilation system for a building

ABSTRACT

A system for heating and ventilating a building which includes a generally peripheral foundation element which supports the external walls of the building. Room air is heated and circulated below the floor and up through floor openings at the external wall. A barrier is connected to the foundation wall so as to span the area enclosed by the foundation wall at a level beneath the floor. Exhaust air is conducted to a region beneath the barrier for surface-enlarged contact with the underside of the barrier. The foundation element and/or the base that supports the foundation element is permeable to air along essentially its full length beneath where the foundation element connects with the barrier and exhaust air flows out through the foundation element or its supporting material while effecting an exchange of heat therewith.

FIELD OF THE INVENTION

The present invention relates to a system for heating and ventilating abuilding which includes a generally peripheral foundation wall or edgebeam which supports the external walls of the building, a floorconstruction which defines residential floor areas in the building, aspace located beneath the floor construction and contained within thefoundation wall, and openings which pass through the floor constructionin the proximity of the external walls of the building to enable air topass from said underlying space to the residential areas of thebuilding.

BACKGROUND OF THE INVENTION

A system of this kind is known, for instance, from SE-B-468 441, wherethe building foundations beneath the floor define a space which can bereferred to generally as a miniature cellar or crawl in space. Thisspace is thermally insulated and is sufficiently large to accommodateservice equipment such as heat exchangers, water heaters, water andsewage connections, and the like. Exhaust air is ducted from thebuilding interior to a heat exchanger in the service space and thendischarged as extract air from the foundations/the building toatmosphere through an outlet duct. Ambient or outdoor air is taken assupply air through an inlet duct and passed to a heat exchanger for heatexchange with the exhaust air, from where the supply air is passed tothe service space. The supply air is then passed from the service spaceto the residential areas in the building, through a slot which extendsaround the perimeter of the external walls and the floor.

One problem with known foundations of this kind is that a heat exchangeris needed for the exchange of heat between the supply and the exhaustair. Another problem is that such heat exchangers must be cleanedregularly. Yet another problem with such known systems is that thecirculation of air in the residential areas/the utility areas isdetermined by the flow of supply and exhaust air to and from thebuilding. A further drawback is that the service space must be given asize which will enable the space to accommodate the heat exchanger orheat exchangers and to afford room for them to be cleaned. The servicespace must also be heavily insulated.

SUMMARY OF THE INVENTION

An object of the invention is to provide a system which will enable thefloor to be heated with the aid of relatively simple means and therewithat relatively low costs, by passing and attemperating air from theresidential areas of the building through the space beneath the floorinto surface enlarged contact with the underside of the floor. Anotherobject of the invention is to provide a system which utilizes asubstantial part of the energy contained by the building exhaust airwithout requiring the use of a true heat exchanger to this end.

Important features of the inventive system are that:

air circulating in the residential areas is attemperated and circulatedinto heat exchange contact with the underside of the floor overessentially the whole area of the floor;

an impervious barrier is disposed beneath the floor construction underwhich the circulated air flows (this floor construction may be aself-supporting floor or a ground-supported floor structure);

the barrier is connected sealingly to the building foundation elementsthat support the external walls of the building, such as to screen thespace horizontally inwards of the foundation elements;

an exhaust air duct leads exhaust air from the residential areas downthrough the barrier, wherein the barrier and the ground base in thefoundations define a space through which the exhaust air is driven fromits exiting location in the gap in a direction towards the foundationelements, to essentially all longitudinal sections thereof;

in the region beneath where the foundation element adjoins the barrierthe foundation element and/or the base supporting said foundationelement is permeable to air along essentially its full length, wherewithexhaust air is able to continue to flow generally radially outwardsthrough the gap and further through the foundation element or itssupporting base while transferring heat thereto.

The exhaust air is then allowed to flow to the surrounding atmosphere.The air-permeable material may extend to the vicinity of the groundsurface outside the edge beam/foundation wall.

In the case when the barrier lies on the ground inwards of thefoundation wall/the edge beam and has, for instance, the form of amembrane, eg a plastic membrane, the air-permeable material (thefoundation element supporting base) may extend conveniently over thewhole area of the foundations, or at least over the areas in whichequipment is to stand.

The exhaust air delivers its heat content to the ground underlying thefoundations and also to the air-permeable material and/or to the edgebeam/foundation wall, so that the heat carried by the exhaust air willhave slowly been extracted therefrom before the exhaust air as extractair is conducted to the surrounding atmosphere, while at the same timethe barrier has kept the exhaust air separate from the circulation airand possibly also from a service space beneath a self-supporting floorstructure.

The inventive system provides a number of advantages, as will be evidentto the person skilled in this art. One advantage is that after beingheated, the circulating indoor air will heat the floor structure; thisenables the air circulating in the residential areas to have a lowertemperature while maintaining a subjective comfort level.

Another advantage is that the ventilation exhaust air delivers its heatcontent to the ground and to the foundation wall/edge beam, so as toreduce the heat that is lost from the circulation air to the foundationwall and to the ground beneath the building.

Another advantage is that the air in the residential areas can becirculated at a rate of flow which is generally independent of the flowrate of the supply/exhaust air. According to one preferred embodiment ofthe present invention the supply air can be mixed with the circulationair without the use of a heat exchanger, wherein the supply air can becontrolled in a known manner so that it is not released into theresidential areas until the temperature of the supply air is generallythe same as that of the circulating air. For instance, the supply aircan be conducted along a circulation air duct that extends through aheat exchanger and thereafter down into the surface-enlarged spacebeneath the floor. Alternatively, the supply air can be introducedthrough a large number of perforations distributed in the roofinsulation and/or wall insulation of the building, such that the supplyair will enter the residential areas of the building relatively slowlyand therewith have time to be heated to the average temperature of thecirculation air before arriving at the central parts of the residentialareas.

This obviates the need of heat exchangers in the system, which not onlyresults in a corresponding reduction in costs, but also removes the needto frequently clean the heat exchangers.

The introduction of air to the residential areas from the perimeter ofthe floor structure results in a favourable circulating air pattern.

The circulation of exhaust air through the foundations and therewithheating of the lower parts thereof, prevents the formation of harmfulmoisture contents in the building/foundation materials.

When the floor structure is a self-supporting structure, the inventivesystem can use a floor which is constructed from a relatively loaddistributing slab or plate which is carried by flexurally rigidlattice-work structures capable of receiving and supporting conduits,such as electric cable ducting, liquid carrying conduits, gas conduitsand the like and therewith facilitate installation of such conduits orducts in the building, wherein water heaters, fans, electric cabletrunking etc. can be placed in a space beneath the floor. It will beunderstood that the free-supporting floor may have some otherconventional construction, for instance a reinforced concrete slabconstruction, in which case the conduits are attached to the undersideof the floor with the aid of conventional fasteners. The barrier may beplaced on the sub-surface in said space and may optionally be coveredwith a protective layer to prevent damage when walked on. The serviceequipment may therewith be placed on top of the membrane and thecirculation air allowed to flow through the bottom space which isdownwardly delimited by the membrane. Alternatively, the membrane may bemounted on the underside of the flexurally rigid structures after havinginstalled the cables, ducts and conduits, wherewith the barrier may havethe form of sheets of plaster board, plywood, air-impervious insulatingboard or like materials.

It will be readily understood that in principle the air-permeablematerial should be placed solely beneath the junction of the barrierwith the edge beam/foundation wall.

The air-permeable material can then have the form of a gravel bed or abed of like material beneath the foundation wall/the edge beam.Alternatively, or in addition, the edge beam/foundation wall itself maybe made air permeable in the sub-barrier region thereof. For instance,the sub-region of the edge beam/foundation wall may be provided with aplurality of perforations configured to effect the transfer of heat withthe mass of the edge beam/foundation wall. However, it is alsoadvantageous to provide a layer of air conducting material, such as agravel bed, in those parts of the foundations at which the barrier liesagainst its underlying supporting surface.

In the aforegoing the invention has been described with reference towinter conditions, in which heat is delivered to the building with theintention of lowering heating costs. The inventive system also hasbenefits in the summer season when wishing to keep the building cool, byenabling the circulating air to be cooled. In this case, the floorsurface is cooled so as to give a subjective impression that the floortemperature is lower than the actual air temperature in the residentialareas.

The invention will now be described with reference to exemplifyingembodiments thereof and with reference to the accompanying drawings, inwhich

FIG. 1 is schematic cross-sectional view of a building equipped with aninventive system;

FIG. 2 illustrates schematically an alternative positioning of themembrane in a building of the kind shown in FIG. 1;

FIG. 3 shows schematically positioning of the membrane in a building inwhich the floor structure rests directly on the ground; and FIG. 4 is aschematic part-sectioned view taken on the line IV--IV in FIG. 1.

Referring to FIGS. 1 and 4, there is shown a building which has agenerally closed ring-like foundation 1 that supports a structural 2comprised of floor elements 21 (see FIG. 4). Each of the floor elements21 has a surface-enlarged top flange 22, a much narrower bottom beamelement 23 and a flexurally rigid latticework construction 24 whichconnects the top flange 22 with the bottom beam element 23. The flanges22 define a sub-floor structure 25. An air gap 26 is provided betweenthe sub-floor 25 and the foundation wall 1 or the external walls 11 ofthe building, said gap extending essentially along the full length ofsaid walls.

As illustrated, the roof insulation 30 is of a known porous kind andambient air is able to seep relatively slowly into the building interiorand into the residential or living areas 32 of the building as supplyair, due to sub-pressure conditions prevailing in the building. Theinsulation 30 may be provided with an air-permeable pressure-equalizinglayer, for instance a layer of fabric, which offers a resistance such asto cause the air to be distributed generally uniformly across theinsulated area. Located beneath the sub-floor 25 is a service space orutilities space 3 whose bottom defining surface is delimited by animpervious barrier 15, in the illustrated case a membrane, eg made offlexible plastic sheet, wherein the edges of the barrier are sealinglyconnected to the foundation wall 1 around the perimeter thereof andbeneath the base floor structure 2. The barrier may have aheat-insulating character and may, for instance, be comprised of a sheetof impervious flexible expanded plastic or cellular plastic. The space 3accommodates a water heater 41, a fan unit 42 and a fan unit 44.

A circulation air duct 50 draws in air from the residential areas 32 andconducts the air to the fan unit 42 installed in the utilities space 3,wherein the circulation air may optionally be heated in heating unit 43prior to be brought into contact with the underside of the floorstructure 25, where the air can disperse in surface-enlarged contactwith the sub-floor 25 to the gap 26 while heating the surface of thefloor 25 (floor heating). The air exiting from the gap 26 rises in theresidential areas 32 and is recirculated through the openings in theduct 50.

Exhaust air is evacuated from toilet, bathroom and kitchen facilitiesthrough an exhaust air duct 60, which conducts the air to a fan unit 44.The fan unit 44 may optionally be fitted with a typical filter unit andfunctions to lead the exhaust air through the impervious barrier 15 andto the central space 7 between the membrane 15 and the ground. In orderto enlarge the specific area of contact of the exhaust air/supply airwith those parts of the foundations at which the barrier 15 lies againstthe floor of the space 3. In these locations, the space floor may becomprised of a layer of air-permeable material, such as a layer ofgravel or like material. Similar gravel beds may be placed beneath thefoundation walls 11 to establish a means of communication of the exhaustair with the outdoor surroundings, in a direction out from theintermediate space 7 and beneath the walls 1.

It will be seen from FIGS. 1 and 4 that the flow rate of exhaust air canbe made selectively independent of the rates of flow of circulation airin the residential areas of the building and through the utilities orservice space 3.

FIG. 2 shows a variant of the inventive system in which the barrier ismounted on the underside of the structural floor 2, to form a floorspace 27 whose vertical extension or depth corresponds essentially tothe vertical extension of the floor elements 21 minus the thickness ofthe upper flange, therewith to disperse the recirculating air throughthe floor structure. In this embodiment, the barrier 15 may convenientlycomprise panel elements, such as sheets of plaster board, plywood, orthermally insulating and air-impervious material, attached to the beamelements 23. Exhaust air can now be dispersed freely across thecross-sectional area of the foundations, wherein exhaust air/supply aircan be led out through an air-conducting porous layer/bed 17 which holdsthe foundation wall spaced from the ground surface 18. Those parts ofthe foundation wall 1 that are located actually beneath the barrier 15may also in this case be permeable to air.

In the embodiment shown in FIG. 3, the sub-floor 25 is placed directlyon the ground 18, via the preferably thermally insulating barrier 15 anda layer of bed of air-permeable material 17 (a gravel bed or like bed),therewith establishing a circulation-air distributing channelway 27 inthe structural floor 2, the fan unit 42 for recirculated air also beingplaced in the residential area 32 of the building. The exhaust air fanunit 44 is also placed in the residential area 32. The barrier 15 may,eg, be formed by the bottom plate, the insulating layer and/or animpervious plastic sheet.

As will be seen from FIG. 3, supply air can be taken into the buildingin a conventional manner through a duct system which communicates withthe surroundings, said supply air primarily being conducted into thecirculation-air system and to the fan unit, from where the air is passedthrough the air heater and then through the floor structure prior tobeing dispersed in the residential areas 32.

As will be evident from FIG. 1, when practicing the invention only twoducts or channels 50, 60 need pass through the sub-floor 25.

All of the embodiments shown in respective FIGS. 1, 2 and 3 includes animpervious barrier 15 which functions to screen the full area of thefoundations beneath the base floor structure, such that the barrier 15delimits downwardly a circulation space for the air mass in theresidential areas of the building, wherein the circulation air can becaused to heat or warm a floor. The barrier 15 defines upwardly a spacewhich receives exhaust air from the building, said exhaust air beingintended to disperse or spread in the pressurized space defined betweenthe barrier 15 and the foundation wall supportive layer and to passtherefrom through an air-permeable supportive layer beneath thefoundation walls (or through perforations in the foundation wallsbeneath the barrier) to the building surroundings.

As shown in FIGS. 1 and 2, an impervious plastic sheet may be placed onthe ground 18 as protection against the ingress of moisture and radongas, particularly when the floor structure is a self-supportingstructure.

One advantage afforded by the present invention is that in hot weatherthe building can be cooled by coupling a cooling source to thecirculation-air duct 50, for instance the evaporator of a heat pump.

Another advantage afforded by the inventive system is that with the aidof relatively simple means the residential or living areas of thebuilding can be cooled in summer months by discharging exhaust air 60direct to the outdoor surroundings (instead of passing the air downbeneath the barrier 15) and by passing outside ambient air through thelayer 17, the perforated foundation walls 1 and optionally also thelayer 16 so as to cool the air, and thereafter to the residential areasof the building, with the aid of suitable fans, blowers and air ducts.The modification that is required in order to adapt the system to an aircooling mode in summertime, by heat exchange with ground-cool masses,will be obvious to the person skilled in this art. For instance, asshown in FIG. 3, this modification may include the provision of a branchconnecting pipe in the duct 50 immediately upstream of the fan unit 42,and the provision of a switching valve downstream of the outlet of theair duct 60 to the fan unit 44, and the provision of a duct from thevalve directly to the surrounding outdoor atmosphere.

I claim:
 1. A system for heating and ventilating a building, said systemcomprising:a generally peripheral foundation element supporting externalwalls of the building, a sub-floor structure defining a floor surface ofresidential areas in the building, an open space located beneath thesub-floor structure and adjacent the foundation element, andair-throughflow openings passing through an air gap defined between thesub-floor structure and the external walls of the building, a barrierconnected to the foundation element so as to span the open spaceenclosed by the foundation element at a level beneath the sub-floorstructure, duct work for conducting building exhaust air to a regionbeneath the barrier, the foundation element in a region beneath wherethe foundation element connects with the barrier being permeable to airso that exhaust air is able to flow out as extract air by the foundationelement, and air circulating means with an air attemperating device forcirculating air from the residential areas of the building into the openspace beneath the sub-floor structure and above the barrier toattemperate an underside of the sub-floor across essentially the wholearea of the floor and to attemperate the circulation air prior topassing the air to beneath the sub-floor and releasing the attemperatedair through the air gap.
 2. A system according to claim 1, wherein thebarrier is located above said air attemperating device.
 3. A systemaccording to claim 2, wherein the exhaust air passes beneath thebarrier.
 4. A system according to claim 2, wherein the open space is aservice space for accommodating service equipment.
 5. A system accordingto claim 1, wherein the air-permeable region is a gravel bed extendingacross at least a part of an area of a supportive surface locatedinwardly of the foundation element.
 6. A system according to claim 5,wherein the sub-floor structure is self-supporting and the barrier liesessentially on a bottom of the open space.
 7. A system according toclaim 1, wherein outdoor air introduced into the building is heated andmixed with temperated indoor air from the residential areas of thebuilding.
 8. A system according to claim 1, wherein the attemperatingdevice heats circulation air.
 9. A system according to claim 1, whereinthe attemperating device cools circulation air.